In the manufacturing of bevel gears, a burr (also referred to as a primary burr here) can arise, for example, at the outer tooth end due to the cutting machining. Because of the high risk of injury, but also because of the risk of complete hardening when hardening the bevel gears, these tooth edges are frequently broken by a chamfer in the scope of chamfering/deburring.
In the described chamfering, depending on the constellation, a secondary burr can result on the bevel gear upon the removal of the primary burr. If the primary deburring is performed using a deburring tool, the cutting edge(s) of which are guided outward coming out of a tooth gap, the secondary burr thus results on the outer circumference of the bevel gear, as shown in FIG. 1A. In contrast, if the deburring tool is guided from the base F to the head K of the bevel gear 10 (into a tooth gap 14) during the primary deburring, the secondary burr thus results in the functional region of the bevel gear 10. In mass production, the primary deburring is therefore carried out in most cases from the inside to the outside, as symbolized in FIG. 1A by the block arrow P1.
A corresponding example is shown in FIG. 1A. A primary burr primarily occurs at the tooth edge 11.1 of the concave flank 16.r, since this flank 16.r generally forms a relatively acute angle γ with the rear face 17 of the bevel gear tooth 10. If only the primary burr 20 were removed at this tooth edge 11.1 (for example, by using a brush), a very sharp tooth edge 11.1 would remain standing. Therefore, a chamfer is usually created at least in the region of the tooth edge 11.1 by chamfering.
The situation after the chamfering of the tooth edge 11.1 is shown in FIG. 1B on the basis of the bevel gear 10 of FIG. 1A. The profile of the first chamfer 12 can be schematically seen in FIG. 1B. As can also be seen in FIG. 1B, a secondary burr 21 can form along the first chamfer 12.
However, secondary burr 21 does not always occur. Relationships have been shown here, for example, with the quality of the cutting edges of the deburring tool. As long as the deburring tool has sharp cutting edges, the primary deburring runs relatively reliably. As cutting edges become blunter, the material of the bevel gear 10 is no longer cut, but rather displaced. In this case, the tendency toward forming secondary burr increases. Since the tooth edge typically does not have a linear profile between bevel gear teeth 15.r, 15.1 and, for example, the heel Fe of the bevel gear 10, the thickness of the chips to be removed during the chamfering varies. For this reason, secondary burrs can sometimes arise.
In contrast, if one moves the deburring tool into a tooth gap 14 during the deburring, the secondary burr can thus arise in the functional region of the bevel gear 10. This approach is therefore not readily selected in mass production.
There is a further aspect which can have a significant influence on the deburring. To be able to perform the deburring in a continuously running procedure, a fixed positive coupling of the rotational movements of the deburring tool and the bevel gear 10 is required. Depending on the type of drive of the deburring tool (a belt drive is sometimes used here), however, it can occur that the rotational movement of the deburring tool begins to lag. This can occur above all if excessively large cutting forces occur on the deburring tool during the deburring. The positive coupling now causes the deburring tool to eat farther into the material of the bevel gear in the event of lagging of the deburring tool, however. In the case of lagging, the deburring tool attempts to cut a chamfer which becomes larger and the cutting forces increase further. This effect can result in destruction of the deburring tool.
There is still a further aspect which plays an important role in bevel gear manufacturing. Because of economic boundary conditions, the bevel gear manufacturing—at least if it relates to mass production—is to be optimized in all its sequences, on the one hand, to use resources carefully and, on the other hand, to be able to machine as many bevel gears as possible per unit of time.
The deburring described at the outset is a partial process of bevel gear manufacturing. There also appears to be potential for further improvements of the sequences in this partial process.
Therefore, on the one hand, the need exists to deburr bevel gears reliably and safely. Especially in the mass production of bevel gears—for example, in automobile construction—the problems which result in conjunction with primary burr and secondary burr have to be avoided.
On the other hand, the need exists to make the deburring more efficient.